Breech bolt latching mechanism



arch 25, 1947. F. l. RATAICZAK 2,418,094

BREECH BOLT LATCHING MECHANISM Filed April 26, 1943 3 Sheets-Sheet 1 arch 194? F. a. RATAICZAK BREECH BQLT LATCHING MECHANISM Filed April '26, 1943 3 Sheets-Sheet 2 March 25, 194-7. F. l. RATAICZAK 2,418,094

BREECH BOLT LATCHING MECHANISM Filed April 26, 1943 3 Sheets-Sheet 3 Patented Mar. 25, 1947 UNITED STATES P TENT OFFICE Francis I. Rataiczak', Dayton, Ohio, ass'ignor' to General Motors Corporation, Dayton, Ohio,- a

corporation of Delaware Application April 26, 1943, Serial No. 484,544

Claims.

This invention relates to ordnance and more particularly to a breech bolt retention and release mechanism for use in a machine gun.

The bolt latch mechanism formerly used on certain slower firing machineguns fails to operate when used on the rapid firing machine guns, such as the .50 caliber M-2 heavy barrel Browning machine gun, not only because it cannot withstand the force to which it is subjected by the rapid moving breech bolt but also because it cannot move into latching position rapidly enough. In order to overcome the problems presented by the rapid firing machine gun without slowing up the firing rate, the latch mechanism has been completely redesigned. The redesign of the latch mech'ainsm was greatly complicated by the fact that a very small solenoid mounted on the back plate of the gun has to be used for releasing the latch. Furthermore, the new latch mechanism has to fit into the small space left in the breech housing of a standard Browning machine gun.

It is an object of this invention, therefore, to provide an improved bolt retention and release mechanism for use with the .50 caliber M-Z heavy barrel Browning machine gun, for example, which may be operated by means of a small solenoid mounted on the back plate of the gun.

Another object of this invention is to so construct and arrange the bolt retention and release mechanism that it may be fitted into the existing space within the receiver of a standard .50 caliber Browning machine gun of the type now in use by the United States military forces.

Still another object of this invention is to so construct the bolt retention and release mechanism that it may be added to or removed from guns in the field without interfering with the other mechanism of the gun.

A further object of this invention is to provide a bolt retention and release mechanism which stores up and utilizes some of the energy of recoil of the bolt in assisting the solenoid in releasing the bolt retention mechanism.

A still further object of this invention is to so construct and arrange the parts that the rate of fire is not materially reduced by the addition of the bolt retention and release mechanism.

Another object of this invention is to provide means whereby the latch mechanism will engage fully or not at all.

Further objects and advantages of the present invention will be apparent from the following desc'iption, reference being had to the accompanyi-ng drawings, wherein a preferred form of the present invention iselearly shown.

In the drawings:

Fig. 1 is a vertical longitudinal view with parts broken away showing the bolt retention mechanism mounted in the standard breech housing;

Fig. 2 is a horizontal longitudinal. view with parts broken away;

Fig. 3' is a transverse sectional view taken substantially on line 3-3 of Fig. 2 and shows the position of the parts when the release solenoid is deenergized;

Fig. 4 is a transverse sectional view similar to Fig. 3 showing the positionof the parts just after the solenoid has been energized;

Fig. 5 is a fragmentary sectional view taken on line 5-5 of Fig. 3

Fig. 6 is an exploded pictorial view showing the bolt. retention latch and: the bolt retention latch lifting means;

Figs. 7, 8, 9, and 10 are diagrammatic views intended to illustrate the operation of the bolt retention and release mechanism; and

Fig. 11 is a pictorial view of the latch trigger.

The machine gun as shown in the drawings comprises a breech. casing. generally designated by the reference numeral l which contains the breech mechanism. This casing is rectangular in form and has two side plates 2, 2. The bottom of the casing. is closed by a transverse bottom plate 5 and the top of the casing is closed by the top plate 5. The casing. is closed at the rear by means of the back plate 8 which is vertically movable in the grooves Ill. The plate 8 carries the standard buffer mechanism indicated as an enti'r'ety' by the reference numeral l2.

Reference numeral i6 is used to designate the standard breech bolt which-has been shown in outline only so" as to simplify the disclosure. This breech bolt is provided with notch means 18 in its upper surface as shown in Fig. 1. In order not to complicate unnecessarily this disclosure,

the gun barrel, the shell feeding mechanism, the barrel extension, the accelerator mechanism, the spring which biases the breech bolt to its forward position, and the rest of the mechanism within the breech housing has not been shown. These elements have not been altered and correspond to the construction now in the guns used. by the United States military forces and therefore need no further description.

The bolt retention latch has been designated by the reference numeral 26 and is pivoted on a pin 22 carried by the bolt latch rod 24 (Fig. 2) which is slidably mounted in the bolt latch bracket 26. The spring 28 biases the bolt latch rod towards the rear of the gun or to the left as viewed in Fig. 2. The nut 30 limits the rearward movement of the bolt latch rod so that it cannot move beyond the position in which it is shown in Fig. 2. The bolt retention latch 20 is provided with a pair of claws 32 and 34 which engage the notch means l8 provided in the upper surface of the breech bolt IS. A spring 36 and plunger 38 (Fig. 1) carried by the bolt retention latch 20 biases the latch downwardly into latching position. As shown in Fig. 1 the plunger 38 has its upper end bearing against the top plate of the breech housing. A buffer engaging projection 39 (Fig. 6) is provided on the latch 20 which also assists in keeping the latch in proper alignment.

The bolt latch release mechanism comprises a pair of levers 46 and 42 which are pivoted so as to both rotate about the conventional trigger bar pin 44 carried by the wall of the breech casing as shown in Fig. 2. The levers 46 and 42 are biased apart by means of a spring 46. A pin 46 having a head 56 and having a shank threaded into the lower lever 40 (Figs. 1, 3, 4, and 6) so as to be movable therewith limits the upward movement of the lever 42 with respect to the lever 46. The lever 42 is provided with a sear 52 which cooperates with a trigger 54 as best shown in Figs. 5 to 10. The trigger 54 is arranged to be moved forward within the breech housing by means of a solenoid operated plunger 56. .The plunger 56 forms a part of the solenoid generally designated by the reference numeral 58. The trigger 54 holds the sear 52, together with the upper lever 42, in it downward position, as shown in Figs. 1, 2, 3, 7, 9, and 10, whenever the solenoid is deenergized.

The trigger 54 is slidably mounted within a longitudinally extendin groove 66 provided in the guide block 62. The trigger is biased into the position in which it is shown in Fig. 5 by means of a spring pressed plunger 64 (Fig. 5) carried by the guide block 62. The rearward movement of the trigger 54 is limited by the spring pressed stop 66 (Fig. 2) which is also carried by the guide block 62 as shown in Fig. 2. As the trigger 54 moves to the rear, the sear 52 rides up on the cam surface 55 so as to lift the release mechanism out of the path of the bolt l6 as shown in Fig. 8.

The guide block 62 is carried by the upper plate 5 as shown in Figs. 3, 4, and 5 by means of the threaded extension (Figs. 3, 4, and 5) which projects through the aperture 12 in the plate 5. A nut 14 is threaded onto the extension l6 so as to hold the guide block 62 in proper fixed relationship with respect to the rest of the mechanism. The plate 5 of a standard gun is already provided with a trigger bar stop pin which registers with a hole in the block 62 as shown in Figs. 3 and 4.

The bolt retention latch is provided with a stud 16 (Figs. 1, 2, and 6) which is adapted to be engaged by the upper lever 42 so as to be lifted thereby when it is desired to release the latch so as to fire the gun. In view of the very rapid rate of fire of a machine gun and in view of the inertia of the moving bolt, it is necessary to provide a very positive mean for moving the bolt retention latch into bolt engaging position in a split seconds time. In addition to the spring 36 which at all times biases the bolt retention latch into the bolt retaining position, I have provided an auxiliary biasing means which comprises a spring 18 surrounding a guide pin which has its upper end slidably mounted within the slot 82 provided in the lever 42 (Fig. 6). The lower end of the pin 86 presses against the upper surface of the claw 34 when the claw is held in its upper position whereby the pring 78 tends to push the latch 26 downwardly.

As shown in Figs. 1 and 2 the bolt retention latch 20 is prevented from moving forward any great distance by the bolt latch rod which acts against the spring 28 and is also prevented from moving forward any great extent by means of the bufier element 90 which is provided with a shank 92 pushing against the fiber discs 94. The discs 94 are mounted within the housing 96 and bolted to the upper plate 5 by the bolts 98. The fiber discs 94 are of the same general type now used in the buffer l2 and need no further description. The discs 94 are held in place by means of the square headed plug I65 which is threaded into the member 96. As shown in Fig. l the front bolt 98 engages the one side of the square headed plug I00 so as to prevent the unscrewing of the plug I60.

The operation of the bolt retention and release mechanism may best be described with reference to Figs. 7 through 10 which diagrammatically show the construction and operation of the parts. Thus in Fig. 7 the bolt retention latch 20 i shown in the bolt latching position. In this position the solenoid is deenergized and the trigger 54 is in its rearward position so as to hold the sear 52 together with the upper lever 42 in the down position. In this position the spring 46 is compressed and the springs 36 and '18 are expanded.

Fig. 8 shows the position of the parts when the solenoid is energized. Energization of the solenoid allows the gun to fire without interruption since the bolt latch 20 is then held out of latching engagement with the breech bolt l6. When the solenoid is first energized, the trigger 54 moves forward (to the right as shown in Fig. 8) whereby the lever 42 is free to move upwardly and consequently the spring 46 forces the lever 42 into its upper position against the force of the spring 35. When the lever 42 moves upwardly it lifts the bolt retention latch 26 out of the path of the breech bolt wh ch is then free to move back and forth uninterrupted by the bolt retention latch mechanism. In the forward position of the trigger 54 the cam surface 55 provided on the trigger 54 engages the sear 52 on the lever 42 so as to slightly elevate the lever 42, th pin 48, and the lever 46, whereby neither the latch release mechanism nor the latch 20 interfere with the breech bolt 16 as the bolt l5 moves back and forth during rapid firing of the gun.

Fig. 9 shows the solenoid deenergized and the trig er 54 moved to its rear position under the action of the plunger 64 not shown in Fig. 9 but shown in Fig. 5. In this position the levers 42 and 46 have both moved downwardly thereby allowing the bolt retention latch 26 also to move down under the action of the spring 36. As shown in Fig. 9 the bolt i6 is at this instant in its forward position so that the levers ill and 32 are free to move downwardly.

Fig. shows what takes place when the bolt it moves from the position in which it is shown in Fig. 9 to the position in which it is shown in Fig. lb and shows how energy is stored up by the springs 33, 56 and it so as to furnish the necessary power for snapping the latch into and out of latching engagement with the breech bolt l6. As shown in Fig. 10 the springs 36 and 18 are both under compression whereby both of these springs bias the bolt retention latch into latching position and the lever i2 is out of engagement with the pin it so as not to interfere with the dovmward movement or the latch 28. As the bolt it moves back still farther the parts will move into the position in which they are shown in Fig. 7. It will also be noted that with the parts arranged as shown in Fig. 10, energy is stored in spring 45 whereby the spring 45 serves as a source of power for releasing the latch upon energization of the solenoid 58.

It should be noted that when the parts are in the position in which they are shown in Fig. 8, deenergization of the solenoid 58 will not cause the latch to move into latching position immediately since at this time the bolt it prevents the lever til from moving downwardly and in this position of the lever til the spring 66 holds the lever 32 and consequently the latch 2b in its upper position. Thus it is apparent that after the solenoid is deenergized and before the latch can move into latching position the following operations must take place. First, the bolt It must move forward so as to allow the levers it! and ii: to drop down so that the sear 5?; can catch beneath the trigger it. trigger 5d holds the lever 42 down, the spring 46 exerts no lifting force on the latch pin 76.) Secondly, the spring l8 must be compressed. This can only be compressed when the lever 42 is held down and the bolt it moves to its rear position so as to push up on the latch 26 Thus it is obvious that the latch ill will not mov down the instant the solenoid 53 is deenergized. It is also obvious that when the latch is is ready to move into latching position, the bolt l6 will have far enough to travel to allow the latch enough time to fully engage the rear wall of the notch id in the bolt it. This is an important feature since it prevents partial engagement of the latch and consequent damage to the engaging corners.

In order to simplify the drawings the standard trigger bar has not been shown. However, it is contemplated that the standard trigger bar will be left in any gun equipped with my mechanism. None of the elements added interfere with the trigger bar.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.

What is claimed is as follows:

1. In a rapid firing machine gun; a breech housing; a breech bolt mounted for reciprocation within said housing; means for latching said breech bolt in one position; means operated by movement of said breech bolt for storing energy derived from the recoil of said breech bolt; and means utilizing said stored energy for releasing said latch means from latching engagement with said breech bolt; said means for storing energy comprising a pair of levers, means for pivotally (Note that when the mounting said levers at one end within said breech housing, and a spring means biasing the free ends of said levers away from one another, one of said levers being arranged in the path of movement of said breech bolt whereby upon movement of the breech bolt said spring is compressed and energy is stored therein.

2. In combination, a rapidly reciprocating member, a latch for stopping said reciprocating member in a given position, means for biasing said latch into latching engagement with said reciprocating member, a first projection on said latch, a second projection on said latch, a pivoted lever arranged to engage one of said projections so as to release said latch, spring means biasing said lever into latch releasing position, means whereby reciprocation of said member loads said spring means, trigger means for preventing movement of said lever into latch releasing position, and spring means between said lever and the other of said projections biasing said latch into latching position when said trigger means prevents movement of said lever.

3. In combination, a rapidly reciprocating member, a latch for stopping said reciprocating member in a given position, means for biasing said latch into latching engagement with said reciprocating member, a first projection on said latch, a second projection on said latch, a pivoted lever arranged to engage one of said projections so as to release said latch, spring means biasing said lever into latch releasing position, means whereby reciprocation of said member loads said spring means, trigger means for preventing movement of said lever into latch releasing position, spring means between said lever and the other of said projections biasing said latch into latching position when said trigger means prevents movement oj said lever, and means for operating said trigger means.

4. In a rapid firing machine gun, a breech casing, a breech bolt mounted for reciprocation within said breech casing, a bolt latch for latching said breech bolt in a fixed position, a bolt latch bracket carried by said breech casing, a bolt latch rod mounted for reciprocation within said bolt latch bracket, spring means for biasing said bolt latch rod towards the rear of the gun, means for p-ivotally mounting said bolt latch on said bolt latch rod, second spring means interposed between the upper wall of said breech casing and said bolt latch for biasing said bolt latch into latching engagement with said bolt, a latch lifting lever, means for pivotally mounting said lever within said casing at a point between said bolt and the upper wall of said casing, spring means for biasing said lever upwardly, trigger means for holding said lever out of latch lifting position, means for compressing said last named spring means upon reciprocation of said bolt, and means for operating said trigger means so as to release said last named spring means for lifting said lever and said latch against the action of said second spring means.

5. In a rapid firing machine gun; a breech housing; a breech bolt mounted for reciprocation within said housing; means for latching said breech bolt in one position; means operated by movement of said breech bolt for storing energy derived from the recoil of said breech bolt, and means utilizing said stored energy for releasing said latch means; said means for storing energy comprising a pair of lovers, means for pivotally mounting said levers at one end within said housing above said breech bolt with the free end of the one lever above the free end of the other lever, a spring means biasing the free ends of said levers away from one another, and means for holding the free end of the upper lever down so as to push the free end of the lower lever into the path of movement of said breech bolt whereby upon movement of the breech bolt said spring is compressed and energy is stored therein for subsequently releasing said latch means.

FRANCIS I. RATAICZAK.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number UNITED STATES PATENTS Name Date Browning Feb. 4, 1919 Bergmann Mar. 2, 1937 Moore et a1 Aug. 11, 1936 Williams May 20, 1941 Turnbull et a1 Oct. 19, 1943 Burnett Dec. 6, 1881 Pedersen Oct. 12, 1920 FOREIGN PATENTS Country Date Swiss Dec. 16, 1935 German Mar. 3, 1939 German July 7, 1932 

